/*
 * @Author : Genustin
 * @Date   : 2012-05-31
 * 求平均年龄
 */
#include <iostream>
#include <cstdio>
using namespace std;

int main()
{
	int num;
	int age;
	double all = 0.0;
	cin >> num;
	for (int i = 0; i < num; ++i)
	{
		cin >> age;
		all += age;
		/* code */
	}
	printf("%.2f\n", all/num);	
	return 0;
}